1. Field of the Invention
The present invention relates to a multi-purpose catalytic distillation column and the use of the column to produce an ether from the reaction of an isoolefin with an alcohol. More particularly the invention relates to the production of tertiary amyl methyl ether by the reaction of the isoamylenes contained within a cracked naphtha stream with methanol in a distillation column reactor which removes the C.sub.6 + fraction, sweetens the feed by removing mercaptans, removes the nitriles in the feed, selectively hydrogenates the dienes in the feed and reacts the isoamylenes with methanol to produce tertiary amyl methyl ether.
2. Related Art
The C.sub.5 refinery cut is valuable as a gasoline blending stock or as source of isoamylene to form an ether by reaction with lower alcohols. Tertiary amyl methyl ether (TAME) is rapidly becoming valuable to refiners as a result of the recently passed Clean Air Act which sets some new limits on gasoline composition. Some of these requirements are (1) to include a certain amount of "oxygenates", such as methyl tertiary butyl ether (MTBE), TAME or ethanol, (2) to reduce the amount of olefins in gasoline, and (3) to reduce the vapor pressure (volatility).
In most C.sub.5 cuts the isoamylene suitable for the production of TAME is frequently present in small quantities, e.g. less than 15%, whereas there are other C.sub.5 olefin isomers and enough dienes and acetylenes to inhibit the etherification process. It is an advantage of the present invention that the contaminants such as the diolefins, acetylenes, mercaptans and nitriles are removed before the etherification in the single distillation column reactor. It also an advantage that the stream recovered from the column containing the ether is suitable without further treatment to be used as an octane blending stock. These and other advantages and features of the present invention become clear from the following descriptions.